I. Technical Field
The present invention relates to a semiconductor device and a method for adjusting characteristics thereof, especially, the present invention relates to a semiconductor device including signal-transmission interconnections preferable for transmitting high frequency signals and the capability to adjust characteristics of the above signal-transmission interconnections, and a method for adjusting characteristics of the semiconductor device.
II. Description of Related Art
Recently, the operations speed of semiconductor devices has increased, in other words, clock frequency thereof has been increased. Since mutual time intervals between high logic signals are shortened due to higher clock frequency, transmitting signals cannot be detected accurately in the case where the rising edge of the clock signal becomes slower. Therefore, a technology that makes rising edges of the clock signal for transmitting signals sharper becomes necessary.
FIG. 23 is a view of a circuit illustrating one conventional technology that makes rising edges of clock signal sharper during transmission of signals. The above technology has a configuration that a plurality of variable capacitance elements 202 are connected to a signal-transmission interconnection 200. At the early stage of the clock rising edge in the signal-transmission interconnection 200, voltage rising is restrained by storing enough charge in the variable capacitance element 202. Subsequently, after enough charge is stored in the variable capacitance element 202, the effect of restraining voltage rising thereof disappears, and then the voltage rises rapidly. As explained above, including the variable capacitance element 202, makes the rising edge of clock signals sharper in the signal-transmission interconnection 200.
In addition, in the signal-transmission interconnection 200, since the charge is released from the variable capacitance element 202 at an early stage of the clock falling edge, voltage dropping thereof is restrained. Subsequently, after enough charge is released from the variable capacitance element 202, the effect of restraining voltage rising thereof disappears, and then the voltage drops rapidly. As explained above, including the variable capacitance element 202 makes the falling edge of clock signals sharper in the signal-transmission interconnection 200 (for example, refer to IEEE JOURNAL OF SOLID-STATE CIRCUITS, VOL. 40 No. 3 MARCH 2005 P744-P752 (FIG. 6))
Characteristics of signal-transmission interconnections in semiconductor device (for example, jitter amplitude) include fluctuation caused by production lines thereof. In the case where the fluctuation is large, it is possible that signals cannot be transmitted accurately at higher frequency. Therefore, a technology for adjusting characteristics of signal-transmission interconnections becomes necessary after the production.